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QUESTION: Dr. Nelson,

I have recently booked a flight between two Russian cities, Kazan to Tyumen. Part of the flight path involves going over a terribly contaminated area known as Ozyorsk.

During the Soviet Union years, there were several accidents that resulted in immense levels of contamination of nearby lake Karachay where much of the nuclear waste was disposed in to. I have read that spending an hour near this lake will deliver a dose enough to cause acute sickness in one hour's time.

So, my question is, is it dangerous to fly over this? Will I receive more of dose than if I were to be flying any other alternative route?

Furthermore, the destination I am headed to is just 395km away from Ozyorsk anyways. Is that a safe distance from such a contaminated region?

Thank you,


ANSWER: Thank you for asking this question, because it allows me several opportunities.  The first being to allay your fears completely, and I'm as skittish about real radiation doses as science tells me I should even imagine.  The second being to ask you where you got your information, because I know quite a bit about this topic.

Here's the thing...either wade through this if you want to follow my logic, or skip to the end past the -- and get the bottom line.

Firstly, whoever told you about spending an hour "near this site" delivering acute radiation sickness within one hour has neither attended a formal MEIR course put on by AFRRI (google the acronyms, if you're curious about the world experts who helped augment my understanding), nor have they monitored radiation levels in or near that lake. One of the key words is "near," which is not a measured distance.  And they're not talking about the whole lake, which would be a hugely different matter.

I know that I surely wouldn't swim in that lake, for sure.  Internal ingestion of contaminated water can definitely involve the long-term absorption of radioisotopes that will cause a slight increase of risk of cancer.  As someone who went skydiving and twice in a row had his parachute not fully open, I understand how insanely risk can affect that one unlucky person.  But in this case the facts are just false.  If you experience real (not panic-induce, which is actually shockingly common) acute radiation sickness within an hour of exposure, you almost certainly took what is considered a fatal dose.  That's 500 Rem in one acute exposure.

Sounds ridiculous?  In the local area (NOTE: only right where the discharge occurred!!! Also, back in 1991!).  It's actually true for that one spot.  Those facts are undisputed. However, there's the distance thing.  Near is a few meters, at distances you're talking about then the distances are at about a standard flight altitude of 10 thousand meters.  One thousand meters squared is equal to one million times lower dose rate (forgetting the air, and at this distance that is actually significant). 10 times that brings it down another factor of 100, plus more air shielding.  Therefore basically, from 100s of Rem/hr down to less than 1 mR/hr.  1mR/hr is basically what you get every day from naturally-occurring background radiation. And now we're talking about micro Rem and nor milli Rem.  

Will you experience increased radiation?  YES!  You always do on high-altitude flights, due to increased cosmic radiation. Go to and check out what earth-to-sky calculus students do with the Pfotzer maximum if you want more details, but flights have never been linked to increased cancer risk.  That's even under detailed studies of pupulations like pilots.

Now you're talking about a single exposure over a minimal amount of time from 10's of kilometers away.  So, no problem, because you don't know these numbers and I'm here to reassure you that there are people who live within 10's of km away ALL THE TIME who have nothing at all to fear unless it becomes a drinking water issue for them.  And so you also had no way of knowing that 395,000 meters away was even waaaay out of bounds.  That, the trees and hills between you...make any notion of anything outside of the very local area (1 km of the discharge site and any area that might have related ground water withing about 10 km) absolutely out of bounds.


Bottom line, as promised:  If you go there, hover over it at those altitudes or even lower in a helicopter, then fly to the ridiculous distance of your will suffer way less dose than you take every day. Way less than you will just taking a flight to get there, a cross-country flight gives you about a chest x ray (way higher than what you'd get).  Not just low-risk, now risk unless you crash in the lake itself.

I get these questions a lot.  Someone once went to me and asked about canceling a ski trip to British Columbia (mountains, way off of sea coast and thousands of kilometers from Japan where nothing outside the tine prefecture of Fukushima itself is really at risk only a few km away).  I went and explained the volume of the Pacific Ocean, the science behind getting away from where they lived and breathed all that radon...explaining how they'd get so much less radiation if they went skiing and breathed the clean air.  

After a few very lengthy go-rounds of real science against their fear....they canceled their ski trip anyhow.  Despite the fact that they'd get less dose total (even accounting for the flights) be just going on it.  So I hope you're willing to listen to science and not some strange fear.  It kills me a little inside, every time someone who doesn't understand that they are actually radioactive and MUST be to live will give in to ridiculous fears.

Go, and enjoy Russia.  I'm sure you will have such an experience.  Never been there yet, but I'm going for sure when I can someday.  So much science and non-science history.

---------- FOLLOW-UP ----------

QUESTION: Well, that does seem a convincing and thorough answer. Thank you!

As for the information: I don't know where I got it from. I had just done some reading about Ozyorsk/Chelyabinsk-40 by chance some months ago and that was just the overall impression I got from reading about it. I don't even think it was necessarily alarmist, I just started overthinking about it, I guess.

Are you able to, for example, explain the significance of the East Urals Radioactive Trace phenomenon? There are some maps that overlay areas with radiation measurements that I don't really understand how to interpret:

Furthermore, I know nuclear science is not necessarily the same thing as ionizing radiation in the context of medical use (x-rays), but are you able to comment on it at all?

I had some medical procedures done when I was a pediatric called Voiding Cystourethrograms. They are done under fluoroscopy, that is to say live, continuous x-rays while the patient voids their bladder. It's done to see if there is some sort of ureter/bladder issues with reflux or other things like that.

I am 24 now, and I had about 5-6 of these between 1996-2000. So keep in mind that that is old technology. I, however, came across one study in all of the possible literature I could find that tries to quantify the risks of the procedure:

"Results: The overall cancer risk of the VCUG cohort is 1.92-fold (95 % CI=1.34-2.74) higher than that of the non-VCUG cohort with statistical significance. The genital cancer and urinary system cancer risks of the VCUG cohort are respectively 6.19-fold (95 % CI=1.37-28.0) and 5.8-fold (95 % CI=1.54-21.9) higher than those of the non-VCUG cohort with statistical significance. The hazard ratios are higher in genital cancer, urinary system cancer (the major radiation exposure area), and cancer of the abdomen, except for the genitourinary system (the minor radiation exposure area), in sequence. Conclusions: Pediatric VCUG is associated with increased subsequent cancer risk, especially in the genitourinary system."

A 1.92, 6.19, and 5.8 fold increase sounds terribly scary to me. This study only follows up persons younger than 18 who had the study or studies (it is unclear) done between '97 and '08. I'd imagine it only gets worse further in the future. This, I suppose is further compounded given the high amount of dental/orthodontist work I've had on my teeth, which involves frequent x-rays, and probably a pretty standard amount of other x-rays done for broken bones and the like throughout my life.

This also combines with some worries wherein I read that having polythelia (third nipple) is already associated with an increased risk of developing genitourinary and other cancers, and persons born with polythelia often have genitourinary defects on top of that, such as vesicoureteral reflux and duplex ureters. I have polythelia, and I've also had the aforementioned issues when I was young which is of course why I had the aforementioned Voiding Cystourethrograms done in the first place.

Oh yeah, I also once ate chanterelle mushrooms fresh-picked from an area of Austria called Styria. I later found a study that measured caesium/radioactivity from various mushrooms species across the area, and chanterelles were found to have high contamination levels. I don't remember the specifics, but it is believed this is residual contamination from the Chernobyl incident.

I also never wear sunscreen, occasionally burn, and have a bad habit of chewing and swallowing my finger nails, skin, and mucous habitually everyday.

I realize this is a lot of information and probably a lot of it is irrelevant, but if you are able to answer any of it, that would be very well appreciated.

Thanks for your help the first time around, also!


ANSWER: That's a lengthy follow-up, and I'm on travel.  I'll answer it, because these seem pretty simple, but try to split these questions into separate queries.

1)  The Ural question.  40 Ci/km^2 is generally what it would take to make an area uninhabitable, and this map is old.  The material there has decayed significantly and washed away, taking it much further below the levels on the map (which it was already well below everywhere).  Therefore, I wouldn't worry about the larger region except for right near the facilities which released the contamination.  Certainly significant levels from a measurement perspective, but that's far below a biologically significant perspective (from which this is far less significant).

2)  The scans.  These scans result in low dosages.  The statistics on this study are far from exhaustive. 31,000 seems like a lot?  Not when you only have 7.5 cases of cervical cancer (the common one) per 100,000 people.  Proper application of statistics tells you that the actual cancer case numbers (what this study is comparing) means comparing very small numbers to one another, and very subject to severe statistical fluctuations.  In short, this study is way below the numbers you need, and that's before you split the 31,000 people into two groups for those who have and haven't had the procedure.

Understanding these risks and medical effects of ionizing radiation is an important part of my current job.  This procedure is relatively low-dose when you look at many other procedures, and I don't buy the statistics at all.  Even if the risk was (for example) doubled, the overall risk is small and you should spend more of your time worrying about things like driving carefully and staying in shape (heart attack, etc risks) and things like that.  Manage the big risks, ignore small risks that you can't do anything about.

I don't know anything about third nipples.  You'll have to confer with a medical doctor or biologist.

Mushrooms from Austria are fine.  There's a ton of studies on the produce form that region.

Definitely wear sunscreen and try not to burn!  That is a known significant risk.  The rest of that stuff is just unrelated.

---------- FOLLOW-UP ----------

QUESTION: Thanks again.

I just took the flight and it was a smaller jet. I'm not sure if that makes a difference in terms of altitude. It seemed to fly lower than a commercial plane. Perhaps around 9000 meters or so. Does that make some sort of difference?

Also, in terms of VCUGs. Does it matter heavily whether it was done on a 'continuous' fluoroscopic model of machine, or a pulsed one? Obviously the dose would be much lower on a pulsed, but since I had these so long ago I'm assuming it was continuous.

Thanks again,


9000 meters is a standard altitude, and it won't make much of a difference unless the altitude is small compared to the actual area of the lake that is contaminated.  In short, no.

You can't just assume it was continuous.  While that would provide a higher dose, these types of exposures are very minimal, in the worst cases.

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Dr. Stephen O. Nelson


I was at a branch of the University of Texas of the Permian Basin for seven years working on an advanced nuclear reactor. Generation IV nuclear reactors. Radiation safety. Nuclear fusion. Since moved into government nuclear work.


Drew the laboratory design for a Generation IV nuclear research reactor Doctoral research on stellar nuclear fusion reactions if your question is on fusion power.

Ph.D. in physics (nuclear physics), Duke University. Taught physics, radiation safety, and nuclear engineering courses at UTPB for 7 years before moving into government work.

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